At least some analog processors (e.g., quantum processors) provide a plurality of analog computation devices (e.g., qubits) which are controllably coupled to each other by couplers. Problems may be “embedded” on the processor for computation (e.g., by representing the problems as graphs where nodes and edges correspond to computation devices and couplers, respectively). An ideal analog processor of this type would generally allow for direct couplings between any two qubits, but in practice the number of physical couplers provided by the processor is often limited.
Two qubits which do not share a physical coupler may, in some circumstances, be coupled by other techniques. See, for example, U.S. Pat. No. 8,174,305 to Harris. However, these techniques can consume additional computational resources and thus constrain the scope of the problems which may be computed, reduce the accuracy of the results, require additional hardware and/or software, and/or require more time for computation. The degree to which such techniques require such resources for a particular computation will generally depend on how closely that computation maps to the hardware.
Accordingly, the design and selection of an analog processor's topology—that is, the arrangement of computation devices and couplers—is an important aspect of analog processor design. Particular topologies may be better-suited to solving certain classes of problem than others, due to the particular graph formed by their computation devices and couplers (along with, potentially, other factors). For an example of analog processor topologies, see U.S. Pat. No. 8,772,759 to Bunyk et al.
There is thus a general desire for an analog processor topology which permits coupling between arbitrary pairs of qubits with reduced computational overhead in at least some circumstances.
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.